1. Technical Field
The present disclosure relates to an organic light-emitting display device and a method of manufacturing the same and, more particularly, to an organic light-emitting display device capable of efficiently protecting an organic light-emitting unit against lateral moisture infiltration by adjusting the distribution of additives contained in an adhesive unit, and a method of manufacturing the same.
2. Discussion of the Related Art
An organic light-emitting diode (OLED) display device is a self-light-emitting display device in which an organic light-emitting layer is disposed between two electrodes. An electron and a hole are respectively injected from the two electrodes into the organic light-emitting layer, and light is emitted by combining the injected electron and hole.
OLED display devices can be classified into a top-emission type, a bottom-emission type, and a dual-emission type, according to emission directions of light, or can be classified into an active matrix type and a passive matrix type, according to the manner in which the OLED display devices are driven.
An organic material and metal material contained in an OLED display device may be very readily oxidized by external factors such as a moisture (e.g., H2O) or oxygen (e.g., O2). That is, the OLED display device may be very sensitive to environmental factors. If moisture or oxygen infiltrates into an organic light-emitting unit, degeneration of an organic emission layer or oxidization of a metal electrode may occur, thereby resulting in various defects such as dark spots or pixel shrinkage and shortened life. Pixel shrinkage refers to a defect darkened from the edge of the pixel because the interface between the metal electrode and the organic emission layer is oxidized or degenerated by moisture infiltration. If pixel shrinkage continues for a long time, it may cause the entire area of a pixel to be tarnished with dark spots, which can seriously affect the reliability of the OLED display device.
To address these problems, various encapsulation methods for preventing moisture or oxygen infiltration have been applied to OLED display devices. For example, side encapsulation using a shield cap formed of metal or glass, top encapsulation using an adhesive layer disposed on the top of an organic light-emitting unit, or hybrid encapsulation, which is a combination of side encapsulation and top encapsulation, may be used.
Among the aforementioned encapsulation methods, hybrid encapsulation employs a filler and a dam member. The filler encapsulates the top of an organic light-emitting unit, and the dam member is disposed outside the filler to minimize lateral infiltration of moisture or oxygen into the organic light-emitting unit. More specifically, the filler for encapsulating the top of the organic light-emitting unit is configured to fill the interior of the OLED display device to protect the organic light-emitting unit against external shock. The dam member disposed outside the filler serves to bond an upper substrate and a lower substrate and to protect the organic light-emitting unit against lateral infiltration of moisture or oxygen. In particular, the dam member has a curable material and additives such as an absorbent reacting with moisture as main components thereof, and can therefore effectively protect the organic light-emitting unit from laterally infiltrating moisture.
However, as the additives contained in the dam member absorb infiltrating moisture from outside, the volume of the additives expands. For example, if calcium oxide (CaO) is used as an additive for the dam member, CaO changes to calcium hydroxide (Ca(OH)2) by reacting with moisture, thereby expanding the volume of the CaO. If the volume of the additive expands by reacting with moisture absorbed into the dam member, cracks may develop in the dam member, which is formed of a curable material. In fact, delamination, which refers to separation of the dam member from the upper substrate or the lower substrate, may occur. Moreover, due to cracks developing in the dam member and delamination, a large amount of moisture or oxygen may infiltrate into the OLED display device, resulting in potentially serious defects, such as dark spots and pixel shrinkage, that lower the reliability of the OLED display device.
In particular, additives positioned closer to the exterior of the dam member absorb moisture or oxygen in the ambient air more quickly, thereby increasing the defects such a cracks and delamination.